Objective:
Since 1980 the prevalence of childhood obesity is rising quickly. Little is known about the risk factors in preschool children. This study determines the influence of playing outside, sleep time, total screen time and physical activity as risk factors for childhood obesity in preschool children.
Methods:
Cross-sectional survey in a birth-cohort in Drenthe, The Netherlands. At the age of 45 month 767 children were studied. Height and weight were measured to calculate the BMI, parents filled in a questionnaire about sleep time, sedentary behaviour and playing outside. At the age of 60 months 113 children were analyzed for the relationship between physical activity and BMI. Physical activity was measured by tri-axial accelerometers. Associations were analyzed by linear regression analysis.
Results:
At the age of 45 months a longer sleep duration is associated with lower BMI (B: -0.26, 95% confidenceinterval (CI) -0.46 to -0.06, P-value: 0.012). Longer total screen time is associated with a higher BMI (B: 0.20, 95% CI: 0.05 to 0.35; p-value: 0.008) and a lower sleep time (B: -0.11, 95% CI: -0.16 to -0.06; p-value: <0.001). Children with a television on the bedroom has a higher total screen time (mean difference: -0.40 ± 0.17, P-value <0.05), but there is no association with sleep time. Children in a household with two or more televisions has a higher BMI (MD: -0.41 ± 0.16, P-value: <0.05), shorter sleep duration (MD: 0.19 ± 0.06, p-value: <0.01) and longer total screen time (MD: -0.25 ± 0.08, p-value: <0.01) There is no association between physical activity and body mass index B: 0.001 (95% CI: 0.000 to 0.001; p-value: 0.082) in five-year old children.
Conclusion:
In four year old children a lower sleep time and a higher screen time are associated with higher body mass index. Furthermore is a longer screen time associated with a shorter sleep duration and shorter time spent playing outside. Due to the cross-sectional character of this study cause and effect are unclear, more longitudinal survey has to be done.